title: Time-dependent diffusion tensor changes of optic nerve in patients with indirect traumatic optic neuropathy.
abstract: BACKGROUND
  Indirect traumatic optic neuropathy (ITON) is a devastating cause of permanent visual loss. Axonal degeneration, the characteristic pathological change of ITON, cannot be assessed by conventional imaging. Diffusion tensor imaging (DTI) has been widely used as a sensitive non-invasive imaging technique to obtain information on axonal integrity.
  
  
  OBJECTIVE
  To study time-dependent changes in ITON patients with DTI and to provide imaging evidence for clinical diagnosis and therapy.
  
  
  METHODS
  We enrolled 28 subjects with unilateral ITON who underwent detailed ocular examinations and magnetic resonance imaging (MRI) examinations. The differences between injured optic nerve (ON) and contralateral ON were tested. The patients were divided into three groups based on time (from injury to examination). Groups 1, 2, and 3 corresponded to the time taken from injury to examination: <7 days, 7-30 days, and >30 days, respectively. DT magnetic resonance imaging (MRI) differences among the groups were compared, including the relationship between diffusion parameters and mean thicknesses of the peripapillary retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) in the macular area.
  
  
  RESULTS
  Compared with contralateral ON, we observed reduced fractional anisotropy (FA) of injured nerves in group 2. Reduced FA and decreased axial diffusivity (λ//) and increased radial diffusivity (λ┴) and mean diffusivity (MD) of injured nerves were observed in group 3. The mean FA value of injured nerves showed a progressive decreasing trend, and mean λ┴ value exhibited a progressive increasing trend. For injured eyes, the MD and λ┴ increases strongly correlated with the decreased mean thicknesses of RNFL and GCC. Conversely, FA was significantly associated with mean RNFL thickness.
  
  
  CONCLUSIONS
  DT-MRI parameters could be useful biomarkers in detecting ON changes in ITON patients.
authors.affiliation: Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, PR China.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, PR China.
authors.forename: W
authors.initials: W
authors.lastname: Shi
authors.affiliation: Key Laboratory of Complex Systems and Intelligence Science, Institute of Automation, Chinese Academy of Sciences, PR China.
authors.forename: M
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, PR China cjr.wzhch@vip.163.com.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Key Laboratory of Complex Systems and Intelligence Science, Institute of Automation, Chinese Academy of Sciences, PR China.
authors.forename: H
authors.initials: H
authors.lastname: He
authors.affiliation: Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, PR China.
authors.forename: J
authors.initials: J
authors.lastname: Xian
authors.affiliation: Key Laboratory of Complex Systems and Intelligence Science, Institute of Automation, Chinese Academy of Sciences, PR China.
authors.forename: B
authors.initials: B
authors.lastname: Lv
authors.affiliation: Department of Radiology, Beijing Tongren Hospital, Capital Medical University, Beijing, PR China.
authors.forename: F
authors.initials: F
authors.lastname: Yan
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D009413:Nerve Fibers, Myelinated / Q000473:pathology*; D009900:Optic Nerve / Q000473:pathology*; D020221:Optic Nerve Injuries / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D055815:Young Adult
keywords: MRI; Trauma; diffusion tensor imaging (DTI); optic neuropathy (ITON)